Carbon Nanotubes

The effects of carbon nanotubes (CNTs) have been studied in the past and the studies reveal that the CNTs can affect mitochondrial DNA in the heart and its aortic artery and result in onset the atherosclerosis. The immune cells called macrophages trap the nanotubes and die subsequently.

Intratracheal installation of single walled carbon nanotubes in the experimental animals has showed pulmonary inflammation and granulomas. Both, the duration of exposure and material characteristics can affect the respiratory process and induce pathological reaction in lung tissues [21]. Mices exposed to nanotubes have showed substantial DNA damage that persisted for at least 6 months. Also, oxidative damages, leading to atherosclerosis risk have been found in animals' heart, aortas, and lungs. The cytotoxicity apparently follows a sequence order on a mass basis [23]

SWNT>MWNT>C60

Phagocytosis of alveolar macrophage can be impaired at the concentration level of about 0.38 g/cm² in the case of SWNT while injury is induced at 3.08g/cm² in the case of MWNT and fullerene. At these levels, macrophages show necrosis and degeneration. A 3 hour exposure to nanospheres at a concentration of 70gm/m³ results clotting in less than half an hour. While in the blood stream, nanoparticles have been observed entering the blood cells themselves.

Under different situations, suggestions have been given regarding the communication of the risks associated, precautions to be adopted during development of nanomaterials, measurements and safety measures [1, 13, 24, 25, 26, 27, 28]. Collection of the details related to the types of nanomaterials manufactured and methods of manufacturing nanomaterials from various manufacturers seems to be a logical beginning to address the problems related to nanomaterials. Three areas that need favourable attention [29] are toxicological hazard assessment, measurement and detection, and worker protection and industrial hygiene. Nanotoxicology is slated to be helpful by providing data about safety details of engineered nanostructures, devices and the undesirable properties of nanomaterials.

3.0 Conclusions

The health and safety issues related to nanomaterials are in an early phase of analysis and as a consequence it appears to be impossible to draw far-ranging conclusions about the potential hazards and risks related to exposure to these materials with certainty. Very less reports are available about the effects of nanoparticles on species other than humans or about their behaviour in the air, water or soil and accumulation in the food chains. However, the general framework of assessment methodology could be useful, even at this early stage.

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